If you're a big dumb shot thrower, it's OK to jump over the runners' hurdles when they're not using them. You can do it on a cinder track, too, no big deal.
But track hurdles are unidirectional, and you don't want to go over one backwards. Hit the hurdle with your foot going the right way, and it'll topple gracefully behind you as you continue on your way, just like those guys in the Olympics on TV.
Hit it going the other way, and it will stand fast. The top will shatter into a million pieces, but it'll still stop you hard enough to lever you straight into the ground, and you'll be picking cinders out of your hands and face for a week.